Carbon nanotubes obtained by conventional methods, is usually a mixture of carbon nanotubes with different chiralities, and different lengths. The carbon nanotubes with different chiralities have different properties, such as thermal, electrical, optical and mechanical properties. Therefore, the chirality assignment of the carbon nanotubes has great significance for the application of carbon nanotubes.
A carbon nanotube is an ideal one dimensional material which has van-Hove singularities in electron density of states and has high optical sensitivity. Therefore, the chirality of a carbon nanotube can be assigned by various optical phenomena, such as resonance Rayleigh scattering (RRS). In 2001, using a tungsten lamp as white light source, Yu and Brus measured the Rayleigh scattering spectra of single-walled carbon nanotube (SWCNT) bundles, which reveal resonance peaks due to the optically allowed interband transitions in SWNTs. Three years later, supercontinuum (SC) white laser was applied to illuminate individual SWCNTs, which generated more distinct resonance Rayleigh scattering peaks. Though excitonic in nature, the resonance peaks are related to the van Hove singularities (vHs) in the electron density of states, thus enabling chirality assignment of SWCNTs. These resonance Rayleigh scattering peaks in visible region imply that the SWCNTs should appear colored. Considering the fact that vHs are widely spread in the electron density of states of 1-D nanomaterials, the nanoworld illuminated by white light should also be colorful. The displayed color information directly reflects the structures and physical properties of nanomaterials.
Because scattering cross-section of the of 1-D nanomaterials is very small, they are usually invisible under optical microscope, so as difficult to observe and collect. The chiralities of carbon nanotubes are not easily and effectively assigned in prior art.
Therefore the chirality assignment of nanomaterials, especially of CNTs by RRS is highly desirable and has long been attempted.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate at least one present embodiment of optical microscopy system and method for using the same, in at least one form, and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner.